1. Field of the Invention
The present invention relates to slide cover mounting technology and more particularly, to a double sliding stability space-saving slide cover lifting structure for use in an electronic device, for example, tablet computer, for allowing the top cover panel of the electronic device to be moved smoothly and stably in horizontal relative to the base panel thereof and then lifted from a horizontal position to a tilted position.
2. Description of the Related Art
Following development and function improvement of touch control technology, tablet computer has become popular. The LCD screen of a tablet computer is located on the outer surface of the computer for convenient operation.
However, the use of a keyboard is a common practice to most people for, for example, text word input. There are tablet computers that comprise an operating system end arranged at the bottom side of the LCD display panel. Thus, the LCD display panel can be moved horizontally relative to the operating system end and then lifted to a tilted position so that the user can use the keyboard on the operating system end.
To satisfy this operation, a special slide cover mounting arrangement is necessary. The known slide cover mounting arrangement comprises a pair of hinges, a pair of sliding rail holders and sliding rails. However, this design does not allow smooth lifting of the LCD display panel. Gear and gear rack may be added to distribute the applied push force evenly. However, the gear will be disengaged from the gear rack when the user lifts the LCD display panel from the operating system end, and will be pushed back into engagement with the gear rack when the user closes the LCD display panel. Because the gear is not constantly kept in mesh with the gear rack, the LCD display panel may be erroneously biased from position.
U.S. patent application Ser. No. 12/986,353 discloses a slide cover design invented by the present invention and entitled “SLIDE COVERF MOUNTING STRUCTURE”, which includes two hinges bilaterally mounted on the top wall of the base member, two sliding rail holders respectively connected to the non-circular pivot shafts of the hinges, two sliding rails bilaterally mounted on the bottom surface of the cover panel and respectively slidably coupled to a sliding groove on each of the sliding rail holder, two gears pivotally connected between fixed rails on the sliding rail holders, and two gear racks respectively mounted on the cover panel and meshed with the gears. Thus, the cover panel is prohibited from biasing during sliding movement, and turnable about the non-circular pivot shafts of the hinges from a horizontal position to a tilted position relative to the base member.
U.S. patent application Ser. No. 13/035,121 discloses a slide cover design invented by the present invention and entitled “LIFTABLE SLIDE COVER MOUNTING STRUCTURE USING A SHEET METAL BRACKET MECHANISM”, which consists of two hinges, two metal sheet bracket mechanism, two sliding rails, two gears, two gear racks and two supplementary support mechanisms. Subject to the use of the sheet plate bracket mechanisms to hold the sliding rails instead of zinc alloy sliding rail holders, the weight of the liftable slide cover mounting structure is minimized. Further, when the cover panel is opened from the base member, the sheet plate bracket mechanisms are forced into engagement with the supplementary support mechanisms to support the cover panel in position for enabling the user to operate the display screen of the cover panel positively.
In the aforesaid prior art designs, the sliding rails and the gear racks are arranged in a parallel manner, occupying much surface space. In consequence, the size of the tablet PC cannot be minimized. In order to save space, U.S. patent application Ser. No. 13/095,793, which was also invented by the present inventor, discloses a new design entitled “Space-saving slide cover lifting structure”, which consists of a pair hinges, a pair of sliding rail holders, a pair of plastic slide guides, a pair of sliding rails, a pair of gears and a pair of gear racks is disclosed. The gear racks are respectively accommodated in the sliding rails to reduce space occupation, minimizing the width of the assembly of the gear rack and the respective sliding rail. The arrangement of the plastic slide guides prohibits direction contact between the metal sliding rails and the sliding rail holders, avoiding friction noise. However, the single-sided coupling arrangement between the sliding rails and the plastic are slidably coupled to the plastic slide guides are less stable. Further, the sliding rail holders are single-piece members that are not strong enough to support a high load and require much installation space.